Sen. Dick Lugar raised $900,000 in the second quarter and finished June with $3.5 million in cash on hand, according to an email campaign manager Emily Krueger sent to supporters Tuesday.
The six-term Indiana Republican faces state Treasurer Richard Mourdock in what is expected to be a costly and highly competitive primary.
Mourdock is angling to beat Lugar from the right and he has secured support from top conservative activists. However, he is trailing badly in fundraising. Mourdock spokesman Chris Conner said Tuesday evening the campaign had raised more than $300,000 in the second quarter.
Mourdock raised an unimpressive $162,000 in the first quarter of the year, while Lugar raised $974,000.
Both teams had a similar message Tuesday about the grass roots.
“We are heartened by the early givers, grassroots supporters and active volunteers that are helping to spread the word ... about Senator Lugar's work to create more jobs and reduce federal spending,” Krueger said in the email.
"I am encouraged by our grassroots campaign and the momentum we are gaining across Indiana,” Mourdock said in a statement. “We are building a grass-roots organization that will be second to none.”
Mourdock got a boost late last week when the state treasurer picked up the endorsement of influential conservative blogger Erick Erickson.
“While Lugar has been in the Senate fighting against conservatives, Mourdock has been in Indiana fighting for conservatives,” Erickson wrote.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.